2. n-Butane can exist in two different conformations called gauche and anti (Google butane and conformation). Use Molecular Calculator to estimate the fraction of molecules in the gauche conformation at 25 $^\circ$C. $\Delta H^\circ$ can be computed as the difference in heat of formation.

3. Estimate $\Delta H^\circ$ the for the following reaction at 25 $^\circ$C

NH$_2$CHO + H$_2$O $\rightleftharpoons$ NH$_3$ + HCOOH

a. Using bond energies
b. Using Molecule Calculator

4. How does the molecular structure determine the rotational entropy? Find out by constructing a molecule with the largest possible rotational entropy using Molecule Calculator. The largest value I could find was 133 J/molK. Can you beat that?

5. How well do the simple solvation models work?
a. Estimate the solvation energy of NH$_4^+$ using MolCalc?
b. What is the polar solvation energy of NH$_4^+$ in water at 25 $^\circ$C assuming that it is spherical?

6. Why do ionic compounds dissolve in water? Use MolCalc to estimate $\Delta G^\circ$ at 25 oC for the following equilibrium

Wednesday, October 2, 2013

CCH is an overlay journal that identifies the most important papers in computational and theoretical chemistry published in the last 1-2 years. CCH is not affiliated with any publisher: it is a free resource run by scientists for scientists. You can read more about it here.

Table of content for this issue features contributions from CCH editor Steven Bachrach: